


Dean Was an Omega

by omegadeanlovesalphacas



Category: Supernatural
Genre: Alpha Castiel, Alpha Castiel/Omega Dean Winchester, Alpha/Beta/Omega Dynamics, Claiming, First Time, Innocence, Knotting, M/M, Mating Cycles/In Heat, Omega Dean, Submission
Language: English
Status: Completed
Published: 2016-11-02
Updated: 2016-11-02
Packaged: 2018-08-28 14:42:27
Rating: Explicit
Warnings: Underage
Chapters: 1
Words: 1,533
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/8450353
Author URL: https://archiveofourown.org/users/omegadeanlovesalphacas/pseuds/omegadeanlovesalphacas
Summary: Innocent 13 year old Dean has only recently presented as an Omega, and doesn’t know why his neighbor suddenly smells so nice…





	

**Author's Note:**

> Warning! This is an Alpha/omega kink prompt fill. Expect more porn than plot, and lots of power imbalance between Cas and Dean. Mind the warnings and kinks in the tags.
> 
> Anonymous asked:  
> A young Dean *as young as you can take it* having recently presented as an omega, suddenly really curious about his older alpha friend Cas *early to mid 20s*. Maybe he subconsciously begins trying to entice and 'woo' Cas into claiming him. *sly/flirty touches, innocently asking about the large bulge in Cas' pants, etc.*

Being an omega really sucked. That was Dean’s conclusion, since apparently waking up “smelling omega” on his 13th birthday meant that he wasn’t allowed to leave the house alone anymore. He used to be able to ride his bike all over town by himself, now his parents seemed determined to keep him under an armed escort at all times. 

They had promised that after his first heat he could have a little more freedom, once his cycle was predictable. They said they didn’t want him outside by himself when his heat could hit any day.

Dean’s mom had tried to explain, said something about how Alphas have no control when an omega is in heat. Then she’d given him a shoebox and said, “you’ll know what to do with these when your heat hits.”

Dean had only looked in the box once before he shoved it as far under his bed as he could reach. He didn’t even know what his mom expected him to do with plastic dicks, he _had_ a dick, why did he need a fake one?

“Fuck this,” Dean muttered. It only took him a minute to climb out the window and find freedom. 

His bike was locked up in the garage, so Dean would have to move on foot. Which meant there weren’t many options for him, since the arcade and the diner were too far to walk.

That was when Dean saw Castiel doing yardwork a few houses down the street. 

Cas was Dean’s neighbor; a 24 year old Alpha who had just bought his first house. He had a good job apparently, marketing or something. But he wasn’t like most Alphas, he was super nice and would let Dean hang out, eat his food and play video games. Dean wasn’t worried about Cas in the slightest. 

Dean ran down the road, grinning as he neared Castiel. “Hey, Cas!”

Cas looked up and smiled, “Hello Dean!”

As Dean approached he caught an interesting scent. It smelled amazing, Dean wanted to get closer to it. When he realized it was coming from Cas he blinked up at him in innocent confusion. “Are you wearing cologne or something?”

Castiel frowned. “No, I don’t wear-” He stopped, eyes going wide. “Oh. You’ve presented, I can smell it.” He shifted a bit where he stood. “You can scent me now, Dean.”

“Oh,” Dean said. “So that’s what an Alpha smells like? I could tell my parents had a scent after I presented, but it didn’t smell as strong as yours.”

“Ah, yes.” Castiel looked a bit uncomfortable, and Dean didn’t understand why. “Your parent’s scent will be familiar to you, but not as strong as an unrelated Alpha.”

“Oh, okay.” Dean shifted a bit as he felt a bit of slick in his pants. That had been happening more and more lately, and it was definitely up there on Dean’s list of annoying omega things. “Can I use your bathroom?”

Castiel seemed to hesitate for a moment before he let Dean inside. 

* * *

Dean was an omega. Dean was an omega.

_Dean is 13 years old, stop it,_ Cas tried to tell himself.

Castiel shook his head as he followed Dean into the house. He was so completely thrown. Last week Dean had just been a neighborhood kid, but today he was a newly presented omega. A beautiful little omega who currently smelled faintly of slick and probably an impending heat.

When Dean reappeared from the bathroom Cas tried to find a way out of his predicament. 

“You know, Dean, it’s kinda late. Don’t your parents want you home?”

Dean shrugged. “They won’t miss me.” He moved towards Cas, trailing his hand over Castiel’s couch and leaving his scent behind.

Dean approached Cas slowly, curiously, submissively avoiding eye contact. “You seem different, now.” He stepped closer, now just a foot away. He ducked his head and bared his neck, although Cas was pretty sure the boy didn’t even know what he was doing. “Now that I’m an omega am I supposed to behave different around you? My parents haven’t told me much.”

It took all of Castiel’s will power not to scent and bite the exposed neck in front of him. He could _feel_ the primal Alpha part of his brain steadily eroding control over his logical, civilized mind. His cock was swelling, getting harder by the moment.

“No, it’s fine Dean, you don’t have to behave any different,” Cas said, voice straining.

Except the omega clearly was. He looked up at Cas. “Can I ask you something?” He ducked his eyes again. “I presented kinda early, and we haven’t done sex-ed yet.” He bit his lip. “How exactly does a male Alpha and a male omega have sex, anyway? I mean, two dicks? I don’t get it…”

Cas frowned. “I don’t think that’s an appropriate…” 

“Why are your pants bulging out?” Dean suddenly asked. “I’ve heard Alphas are extra big, is that why?” To Castiel’s shock the boy reached out and _touched him._

Castiel reached out and snatched Dean’s hand away from his hard cock. And that was when he smelled it. Slick. Castiel could smell omega slick. Stronger than before, and so very, very sweet.

* * *

Dean was so confused. He just really needed to be closer to Cas. The Alpha was suddenly the most interesting person Dean had ever met and he needed to figure out why he smelled so good. 

But he needed to do that while also making himself smaller. Because he didn’t know why, but he really needed to be small in front of Cas, and he really needed to show the Alpha his neck. He needed Castiel to tell him what was going on, to tell him what to do about it. 

Was this what they called submission?

Dean shifted as he felt the slick gush out of his ass again. He didn’t understand why, it had never been this bad before. He could feel it quickly soaking through his jeans.

When Castiel spoke his voice was rough. “Dean. You need to leave. Now.”

Dean finally looked up and made eye contact with Cas. His eyes were blown wide, dark with something intense.

For some reason the look made Dean drop to his knees. “Alpha. What’s happening? Please…”

“You’re… you’re going into heat,” Castiel managed. “You need to go home. _Now_.”

“But, I want to stay with you,” Dean said. And he did. He wanted Cas, wanted to stay with Castiel forever. And he wanted, needed, something else. His ass was starting to ache and burn, hot and wet with need. It was like an itch, it was a need that Dean had to have filled. Yes, that was it, he needed to be _filled_. “Please, Alpha. Please.”

Castiel suddenly grabbed Dean by the hair and yanked it back, forcing him to make eye contact. “Do you even understand what you’re asking for?”

“Yes.” Dean knew. He didn’t know a lot about sex, but he knew that omegas belonged to Alphas. He liked Cas, he could belong to Cas. He _needed_ to belong to Cas. “Wanna be your omega. Please, Alpha! Please claim me.”

Any control Castiel had was shattered, and he picked Dean up and shoved him onto the couch on his belly. Dean could barely register what was happening as Cas yanked down his jeans and shoved two fingers into his ass.

“Oh!” Dean gasped, jerking his hips in both pleasure and shock. “C-Cas, what are-?” But he lost his words as the fingers pumped in and out of his ass, quickly adding a third one. Then there was suddenly something much bigger pressing against his hole.

Dean cried out as Castiel’s large cock was driven deep inside him. 

Castiel’s mouth pressed to Dean’s ear. “Now you know, little omega,” he growled. His hips pulled out and then drove back in, setting up a fast, _claiming_ pace.

Dean squirmed under the Alpha’s weight, brain shut down from conflicting pain and pleasure. This was nothing like what he expected, but he needed _more_. Even though he didn’t even know what more _was_. 

He soon found out when only a few minutes later the Alpha’s cock started to swell, growing bigger and bigger as it stretched and filled him. He felt he was surely going to be split open, but it was also the most amazing thing he’d ever felt. The giant knot pressed harder and harder on a bright spot of pleasure inside Dean, until he finally came with a cry and a long moan.

Castiel grunted and slammed his knot into place in the omega’s channel. Too far gone to stop himself, he leaned in and bit down hard on the back of Dean’s neck, claiming him. He then collapsed on top of Dean, letting out a long groan as his cock pulsed and steadily pumped his seed into the young omega’s ass.

Dean moaned and pushed back against the knot. Even after coming it felt so good the way it filled him and stretched him.

Claimed him.

He looked back over his shoulder at Castiel. The Alpha looked at him with fond exasperation. “Your parents are going to kill me.”

Dean just grinned.

**Author's Note:**

> Thanks for reading! Comments are love! <3
> 
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